The dental x-ray film processing system and apparatus of Zwettler described in U.S. Pat. No. 4,032,943, provides a compact processor for automatically continuously completely processing typical periapical and bite-wing size films. The apparatus occasionally caused the film to jam somewhere along its excursion due to the film guide track means failing to guide the film properly into succeeding drive roller means. More importantly, the many expensive rubber rollers needed to drive the film through the developing, fixing and rinsing tanks and drying areas require frequent cleaning to prevent the drying and caking of chemicals thereon. In practice, the rollers are infrequently given the necessary maintenance attention.
Further, the working surfaces of each pair of rubber rollers are initially in slight, or near tangential contact in order that the film may be readily received thereinbetween and squeezed gently thereby before proceeding to the next pair of driving rotating rollers. The degree of closeness or contact should be closely controlled if the film is to be drawn through the apparatus smoothly and yet not have its silver stripped or otherwise damaged by roller action or jamming. The rubber material should be maintained within acceptable durometer readings and must not be permitted to become so porous that the solution chemicals will penetrate therein to result in a surfae cake thereon upon drying thereof.
The present invention substantially overcomes both deficiencies of the apparatus of U.S. Pat. No. 4,032,943. That is, by eliminating the V-grooved film guide track means of the patented apparatus and substituting therefor curved deflection guide members, uninterrupted and jam-free travel of the film is substantially insured by accurately directing the leading edge thereof into a successive downstream pair of rotating rollers. Further, the film is always presented properly to the next roller pair with both sides of the film exposed to the respective fluid baths. It must be appreciated that the preiapical and bite-wing x-ray film, even though small, has a tendency to sag when traveling the curvilinear path through the various chemical solutions.
Secondly, at least in the body of the respective tanks and in the drying area, both of the two vertically disposed roller support frames 170 and 172 are molded with a plurality of spaced cut-out portions resulting in a like number of key-hole shaped cantilevered spring segments integral with the roller support frames. By rotatably mounting one roller of each pair to the cantilevered spring segments, we have found that plastic rollers may be used in lieu of the expensive rubber rollers. Additionally, the tight tolerances required to achieve the proper degree of tangential contact, or near tangential contact between the rollers of each pair of rubber rollers is no longer necessary due to controlled spring-action between individual plastic rollers of each pair thereof which automatically maintains them in proper resilient contact.